1. Field
The following description relates to a magnetic resonance imaging method and apparatus in which a resonance frequency of a portion of a predetermined area of a subject is acquired in each section, which corresponds to a repetition time (TR), of a pulse sequence, and the acquired resonance frequency is used to generate a magnetic resonance image of the subject.
2. Description of the Related Art
Magnetic resonance imaging (MRI) is a technique used to acquire an image of a subject by exposing atomic nuclei of the subject to a magnetic field and briefly turning on a radio frequency (RF) current produce a varying electromagnetic field having resonance frequency. Resonance of an atomic nucleus during MRI refers to a phenomenon in which high frequency energy is incident onto the atomic nucleus magnetized by the magnetic field, and the atomic nucleus in a low energy state is excited by absorbed high frequency energy. As a result, the atomic nucleus then reaches a high energy state. Atomic nuclei have different resonance frequencies according to the types thereof, and resonance is affected by the intensity of the magnetic field. The human body includes multitudinous atomic nuclei, such as 1H, 23Na, 31P, 13C, etc., which exhibit a magnetic resonance phenomenon. In general, a proton is used to generate a magnetic resonance image.
In response to a radio frequency (RF) pulse having high frequency energy is temporarily applied to a subject, a magnetic resonance signal is emitted from the subject. The magnetic resonance signal emitted from the subject may be classified according to a type of the RF pulse. Thus, a response to a general RF pulse is referred to as a free induction decay (FID), and a response to a refocusing RF pulse is referred to as an echo signal.
In existing MRI techniques to generate a magnetic resonance image of a predetermined area of a subject, the same resonance frequency is repeatedly used on an entire area of a subject to be imaged in each section of an RF pulse sequence.